Keep the colleague's microbu-esp32c5 tree in this repository

obu-firmware builds against vanetza-idf from microbu-esp32c5/external, but
that tree was gitignored, so a clone of this repository could not build the
firmware it ships. It is now committed here as ordinary files in its own
folder, microbu-esp32c5/: the colleague's commit cf4b99f plus the V2X2MAP
bridge's signature verification (--trust) used on the bench. Nothing is
fetched from or pushed to the colleague's repository; this repository and
its remotes carry everything. The folder's own .gitignore keeps build output,
downloaded components and private key material out, as it did there; the
committed file set is identical to that repository's tracked files.

The ESP32-C5 is still flashed from obu-firmware/, which only takes
vanetza-idf from microbu-esp32c5/, so the two stay separate folders.
FLASHING.md says how to take a newer version of the colleague's tree (copy
it over the folder, rebuild, test, commit).

microbu-esp32c5/external/vanetza-idf/vanetza/net/tests/cohesive_packet.cpp

@@ -0,0 +1,100 @@
+#include <gtest/gtest.h>
+#include <vanetza/net/cohesive_packet.hpp>
+#include <vanetza/common/byte_buffer.hpp>
+
+using vanetza::ByteBuffer;
+using vanetza::CohesivePacket;
+using vanetza::OsiLayer;
+
+TEST(CohesivePacket, ctor_and_size)
+{
+    const ByteBuffer buffer(892);
+    CohesivePacket packet(buffer, OsiLayer::Transport);
+
+    EXPECT_EQ(892, packet.size());
+    EXPECT_EQ(892, packet.size(OsiLayer::Transport));
+    EXPECT_EQ(0, packet.size(OsiLayer::Network));
+    EXPECT_EQ(0, packet.size(OsiLayer::Session));
+}
+
+TEST(CohesivePacket, set_boundary)
+{
+    CohesivePacket packet(ByteBuffer(512), OsiLayer::Link);
+    ASSERT_EQ(512, packet.size(OsiLayer::Link));
+
+    packet.set_boundary(OsiLayer::Link, 64);
+    EXPECT_EQ(64, packet.size(OsiLayer::Link));
+    EXPECT_EQ(512, packet.size());
+
+    ASSERT_EQ(448, packet.size(OsiLayer::Network));
+    packet.set_boundary(OsiLayer::Network, 128);
+    EXPECT_EQ(128, packet.size(OsiLayer::Network));
+
+    ASSERT_EQ(320, packet.size(OsiLayer::Transport));
+    packet.set_boundary(OsiLayer::Transport, 0);
+    EXPECT_EQ(0, packet.size(OsiLayer::Transport));
+    EXPECT_EQ(320, packet.size(OsiLayer::Session));
+    EXPECT_EQ(512, packet.size());
+
+    EXPECT_EQ(448, packet.size(OsiLayer::Network, OsiLayer::Application));
+    EXPECT_EQ(0, packet.size(OsiLayer::Application, OsiLayer::Network));
+}
+
+TEST(CohesivePacket, access)
+{
+    ByteBuffer buffer;
+    for (unsigned i = 0; i < 512; ++i) {
+        buffer.push_back(i);
+    }
+    CohesivePacket packet(buffer, OsiLayer::Network);
+
+    auto net_range = packet[OsiLayer::Network];
+    ASSERT_EQ(512, net_range.size());
+
+    packet.set_boundary(OsiLayer::Network, 128);
+    auto transport_range = packet[OsiLayer::Transport];
+    ASSERT_EQ(384, transport_range.size());
+
+    ByteBuffer::value_type expected_byte = 128;
+    for (auto byte : transport_range) {
+        EXPECT_EQ(expected_byte, byte);
+        ++expected_byte;
+    }
+}
+
+TEST(CohesivePacket, trim_simple_boundaries)
+{
+    CohesivePacket packet(ByteBuffer(128), OsiLayer::Link);
+    EXPECT_EQ(128, packet.size());
+    packet.trim(OsiLayer::Physical, 100);
+    EXPECT_EQ(100, packet.size());
+    packet.trim(OsiLayer::Physical, 130);
+    EXPECT_EQ(100, packet.size());
+}
+
+TEST(CohesivePacket, trim_advanced_boundaries)
+{
+    CohesivePacket packet(ByteBuffer(128), OsiLayer::Link);
+    packet.set_boundary(OsiLayer::Link, 12);
+    packet.set_boundary(OsiLayer::Network, 0);
+    packet.set_boundary(OsiLayer::Transport, 24);
+    packet.set_boundary(OsiLayer::Session, 48);
+    EXPECT_EQ(128, packet.size(OsiLayer::Link, OsiLayer::Presentation));
+    EXPECT_EQ(0, packet.size(OsiLayer::Physical));
+    EXPECT_EQ(12, packet.size(OsiLayer::Link));
+    EXPECT_EQ(0, packet.size(OsiLayer::Network));
+    EXPECT_EQ(24, packet.size(OsiLayer::Transport));
+    EXPECT_EQ(48, packet.size(OsiLayer::Session));
+    EXPECT_EQ(44, packet.size(OsiLayer::Presentation));
+    EXPECT_EQ(0, packet.size(OsiLayer::Application));
+
+    packet.trim(OsiLayer::Network, 24 + 48 + 20);
+    EXPECT_EQ(24 + 48 + 20, packet.size(OsiLayer::Network, OsiLayer::Application));
+    EXPECT_EQ(104, packet.size());
+
+    packet.trim(OsiLayer::Network, 24 + 8);
+    EXPECT_EQ(44, packet.size());
+    EXPECT_EQ(24, packet.size(OsiLayer::Transport));
+    EXPECT_EQ(8, packet.size(OsiLayer::Session));
+    EXPECT_EQ(0, packet.size(OsiLayer::Presentation, OsiLayer::Application));
+}